The Asus Zenfone 3 Max ZC553KL is a hybrid dual-SIM phone, which is a bit of a let down considering the earlier model had real dual-SIM functionality. You can opt for a micro SD card of up to 128GB in place of the second SIM. The phone also has, 32GB of storage and 3GB of RAM, Wi-Fi b / g / n single-band, Bluetooth 4.1, FM radio, and GPS.